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ICEAA.2017.8065374

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Application of Selective Laser Melting to the Manufacturing
of Antenna-Feed Chain Components
G. Addamo1, O.A. Peverini1, D. Manfredi2, F. Calignano2, M. Lumia1, G. Virone1
Abstract This paper presents the research activity carried out
jointly by the CNR-IEIIT and IIT aimed at the design and
manufacturing of antenna-feed chain components by additive
manufacturing and in particular by the selective laser melting
process.
1
INTRODUCTION
The design of modern antenna feed chains for
satellite communications requires to manage at the
same time mechanical and electromagnetic aspects
in order both to reduce envelope, mass and weight,
and to satisfy stringent requirements in terms of
polarization purity, isolation and low loss, usually
over very large operative bands [1]. Moreover, the
trend to operate at higher frequency bands (from
Ku/K to Ka/Q) makes some consolidated
electromagnetic solutions too expensive or even
not feasible exploiting classical manufacturing
processes (like milling or electrical discharge
machining). In this context, further limitations are
related to high-power applications where passive
intermodulation products and multipactor
discharge have to be controlled [2]. Additive
manufacturing (AM) technologies can represent an
interesting solution in this field. Indeed, the
exponential growth of publications on this topic in
the last few years and the formation of various
spin-off prove the enormous interest on this topic
by both industries and research centers [3],[4].
The design flexibility, the cost, mass and waste
reduction are the key points of these technologies,
whereas the drawbacks are related to the relatively
low level of technological readiness, above all in
terms of the necessary accuracy for microwave
applications operating in Ku or higher frequency
bands. In this work, we present the results of an ongoing deep research activity about the additive
manufacturing of passive waveguide components
developed jointly by CNR-IEIIT and IIT.
2
ADDITIVE MANUFACTURING PROCESS
According to the American Society on Technology
and Materials, additive manufacturing (AM) is a
process of joining materials to make objects from
3-D model data, usually layer upon layer, as
opposed
to
subtractive
manufacturing
methodologies [5]. Among the different AM
processes, selective laser melting (SLM) is a layerby-layer technique based on fusing metal powders
by means of a high-power laser beam. It allows the
fabrication of parts directly in metal with 30-100
—m accuracy as a function of the metal used and
parts geometry. A description of the different
process steps can be found in [6].
2
FEED CHAIN COMPONENTS DESIGN
The realization of high performances stop-band
filters operating in Ku/K bands have been first
addressed by exploiting SLM technology. The
requirements are those typical of satellite
telecommunications: reflection coefficient lower
than -30 dB in the pass band [12.5, 15.0] GHz and
transmission coefficient lower than -45 dB in the
stop band [17.5, 21.2] GHz. Among the different
architectures, a composite step/stub resonator [7]
has been exploited. In order to satisfy the
requirements, fifth- and sixth-order filters have
been designed and manufactured. The fifth-order
solution presents a classical straight orientation of
the stub discontinuities, while the sixth-order filter
implements a 45 deg orientation of the stubs in
order to guarantee self-supporting surfaces of the
internal channel when the filter is built layer-bylayer along the waveguide longitudinal axis.
Moreover, for this filter, the designed isolation is 50 dB. The prototypes have been realized using
three different alloys (AlSi10Mg, Ti64Al4V and
Maraging steel) in order to analyze the relevant RF
characteristics and the mechanical accuracy.
Figure 1 shows the two sets of prototypes (i.e. the
fifth- and sixth-order filters). The measured
performances are summarized in Table 1 and show
that the AM oriented architecture (i.e. the 6th-order
filter) enables to achieve better accuracy and,
therefore, a better accordance with the predicted
performances.
________________________________________________________________________________________
1
2
CNR-IEIIT, Corso Duca degli Abruzzi 24, 10129, Torino, Italy; e-mail: [email protected]
[email protected] Corso Trento, 21 - 10129 Torino, Italy.
‹,(((
812
Single
Band Horn
[14,18] GHz
Dual
Band Horn
[12.2,14.6] GHz
+
[17.7,20] GHz
Figure 1. Prototypes of the fifth- (bottom) and sixth(top) order Ku/K band low-pass filter manufactured
through SLM in Maraging Steel (left), Ti64Al4V
(center) and AlSi10Mg (right) powders.
Subsequently, the design of high performances
horns has been addressed. A smooth wall
architecture [8] has been preferred to the classical
corrugated solution, since it is particularly suitable
for the SLM process and at the same time can
guarantee
considerable
performances.
In
particular, single- and dual-band horns have been
designed. The former operates in the frequency
range [14, 18] GHz with a return loss greater than
30dB, a maximum cross-polarization level lower
than -35 dB within the illumination angle of 30 deg
with a field taper between [14, 16] dB. The latter
operates in the frequency ranges [12.2, 14.6] GHz
and [17.7, 20] GHz. In this case, the required
return loss is 23dB, the maximum crosspolarization level lower than -33 dB within 30 deg
and a gain greater than 16 dB. The horns have been
manufactured by SLM in aluminum alloy and,
then, tested in anechoic chamber. An excellent
accordance with the simulated values has been
found as summarized in Table 2.
Acknowledgments
The authors wish to thank G. Dassano with the DET
department of the Politecnico di Torino for the horn
antennas measurements.
Prototype
S11 (dB)
[12.5,15] GHz
S21 (dB)
[17.5,21.2] GHz
5thorder
6thorder
5th order
6thorder
AlSi10Mg
< -23
< -25
< -45
< -52
Ti6Al4V
< -20
< -35
< -52
Steel
< -29
< -35
< -49
< -27
< -30
Return
Loss
Max.
Cross.Pol.
Field
Taper at 30deg
>30 dB
< -35 dB
[14,16] dB
< -23
<-33 dB
[14,18] dB
Table 2. Measured performances of the single- and
dual-band horn prototypes manufactured in aluminum
alloy.
References
[1] M. Schneider, C. Hartwanger and H. Wolf,
"Antennas for multiple spot beam satellites,"
CEAS Space Journal, vol. 2, no. 1, p. 59–66, 2011.
[2] O.A. Peverini, G. Addamo, R. Tascone, G. Virone,
P. Cecchini, R. Mizzoni, F. Calignano, E.P.
Ambrosio, D. Manfredi, P. Fino, ‘Enhanced
Topology of E -Plane Resonators for High-Power
Satellite Applications’, IEEE Trans. on Microwave
Theory and Techniques, 2015, Vol. 63, Issue 10.
[3] P. Booth, J. Gilmore, E. V. Lluch and M. Harvey,
“Enhancements
to
satellite
feed
chain
performance, testing and lead-times using additive
manufacturing", 2016 10th European Conference
on Antennas and Propagation (EuCAP), Davos,
2016, pp. 1-5.
[4] T. Wohlers, “Wohlers Report 2015: Additive
manufacturing and 3D printing state of the
Industry”, Wohlers Assoc. Inc., Fort Collins, CO,
USA, 2015.
[5] ASTM F2792-12a: Standard Terminology for
Additive Manufacturing Technologies (Withdrawn
2015), ASTM International, West Conshohocken,
PA, 2012.
[6] F. Calignano, D. Manfredi, E.P. Ambrosio, L.
Iuliano, and P. Fino, “Influence of process
parameters on surface roughness of aluminum
parts produced by DMLS”, International Journal of
Advanced Manufacturing Technology., vol. 67, no
9, pp. 2743-2751, August 2013
[7] O.A. Peverini, M. Lumia, F. Calignano, G.
Addamo, M. Lorusso, E. Ambrosio, D. Manfredi,
G.Virone, “Selective Laser Melting Manufacturing
of Microwave Waveguide Devices”, Proceedings
of the IEEE 2017 Issue 99.
[8] S. K. Rao, “Design and Analysis of MultipleBeam Reflector”, IEEE Antennas and Propagation
Magazine, Vol. 41, Issue 4, pp. 53-59, August
1999.
Table 1. Measured reflection (in pass band) and
transmission (in stop band) coefficients of the filter
prototypes manufactured in different alloys.
813
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